-- ============================================================================
-- 反馈回复：官方回复 + 用户端未读提醒（幂等，可重复执行）
--
-- 本迁移与 internal/logic/migrate.go 的 migrateColumns() 内容一致：
-- 服务端启动时 Migrate() 会自动加列（项目约定：升级只需重启服务）。
--
-- 新增列：
--   feedbacks.reply_content  官方回复内容
--   feedbacks.reply_by       回复管理员 id，0=无
--   feedbacks.reply_at       最近回复时间
--   feedbacks.reply_read     用户端已读：0有新回复未读 1已读
-- ============================================================================

SET @db := DATABASE();

SET @sql := (
  SELECT IF(COUNT(*) = 0,
    'ALTER TABLE `feedbacks` ADD COLUMN `reply_content` varchar(1000) NOT NULL DEFAULT '''' COMMENT ''官方回复内容''',
    'SELECT ''feedbacks.reply_content already exists'' AS msg')
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = @db AND TABLE_NAME = 'feedbacks' AND COLUMN_NAME = 'reply_content'
);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @sql := (
  SELECT IF(COUNT(*) = 0,
    'ALTER TABLE `feedbacks` ADD COLUMN `reply_by` bigint NOT NULL DEFAULT 0 COMMENT ''回复管理员 id，0=无''',
    'SELECT ''feedbacks.reply_by already exists'' AS msg')
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = @db AND TABLE_NAME = 'feedbacks' AND COLUMN_NAME = 'reply_by'
);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @sql := (
  SELECT IF(COUNT(*) = 0,
    'ALTER TABLE `feedbacks` ADD COLUMN `reply_at` datetime DEFAULT NULL COMMENT ''最近回复时间''',
    'SELECT ''feedbacks.reply_at already exists'' AS msg')
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = @db AND TABLE_NAME = 'feedbacks' AND COLUMN_NAME = 'reply_at'
);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;

SET @sql := (
  SELECT IF(COUNT(*) = 0,
    'ALTER TABLE `feedbacks` ADD COLUMN `reply_read` tinyint NOT NULL DEFAULT 0 COMMENT ''用户端已读：0有新回复未读 1已读''',
    'SELECT ''feedbacks.reply_read already exists'' AS msg')
  FROM information_schema.COLUMNS
  WHERE TABLE_SCHEMA = @db AND TABLE_NAME = 'feedbacks' AND COLUMN_NAME = 'reply_read'
);
PREPARE stmt FROM @sql; EXECUTE stmt; DEALLOCATE PREPARE stmt;